Assange has been sheltering in the embassy since June to avoid extradition to Sweden to face rape and sexual assault allegations. Britain says it is obliged to send him to Sweden and will not let him to go to Ecuador, which has given him asylum.

His lawyers and the Ecuador government fear that travelling to Sweden could lead to the 41-year-old Australian's extradition to the United States, where he could face charges stemming from Wikileaks' publication of thousands of US diplomatic cables.

Challenged in a CNN interview in the embassy that he could not stay there forever, Assange said:

"I think we need the US government to drop its investigation ...
It's an immoral investigation. It breaches the First Amendment. It breaches all the principles that the United States government says that it stands for and it absolutely breaches the principles that the US founding fathers stood for and which most of the US people believe in."

Video courtesy of CNN International

Ecuador wants Britain to give Assange written guarantees that he would not be extradited from Sweden to any third country. Assange fears he could face inhumane treatment in the US.

"There's an attempt to extradite me without charge and without evidence, allegedly for the purpose of questioning," he said. "All meanwhile, the FBI has been engaged in building this tremendous case."

In the interview, Assange likened life in the embassy to "living on a space station".

"There's no natural light," he said. "You have got to make all your own stuff. You can't go out to the shops."

"But I've been in solitary confinement. I know what life is like for prisoners – it's a lot better than it is for prisoners."

Earlier on Thursday, Wikileaks began publishing what it said were more than 100 US defence department files detailing military detention policies in camps in Iraq and at Guantanamo Bay in the years after the Sept. 11 attacks on US targets. – Reuters